1. Field of the Invention
The invention relates to crosslinkable compositions on organosilicon compounds which comprise heterocyclic substituents, to processes for preparing them, and to their use.
2. Description of the Related Art
One-component sealants which are storable with exclusion of water and which vulcanize to elastomers at room temperature on ingress of water (RTV-1 compositions) have been known for a long time. These products are used in large quantities in the construction industry, for example. The basis of these mixtures are polymers terminated by silyl groups which carry reactive substituents such as OH groups or hydrolyzable groups such as alkoxy groups, for example. Of importance for professional applications in particular are neutrally crosslinking sealants which comprise large amounts of fillers, since compositions of this kind have particularly good processing properties. Of interest for this purpose are, in particular, what are called alkoxy-crosslinking sealants, since in the course of the curing they do not give off elimination products that are objectionable from a health standpoint.
These sealants are typically subjected to particularly exacting requirements in terms of their adhesion to a multiplicity of different substrates. This function is commonly resolved by adding organofunctional silanes as adhesion promoters. Reference may be made here, in particular, to U.S. Pat. No. 5,093,454, which describes an adhesion promoter combination of silyl-substituted isocyanurates and epoxy-functional silanes. The compositions described therein using alkoxy-functional silanes are not stable on storage, however, but instead cure fully within a short time when the polymer components are mixed with the crosslinkers. Such compositions are of no interest for construction applications.
In addition to good substrate adhesion, sealants for construction applications are required to exhibit a low 100% tensile strain, usually termed “modulus”. The 100% tensile strain for such low-modulus sealants must in general be less than 0.4 MPa. Furthermore, it is absolutely necessary for the products to possess very good storage stability, so that they still possess flawless functioning even at the end of their guaranteed storage life. Good processing properties, in addition, require that the composition be modelable, something which is typically achieved by adding a large amount of fillers.